DocumentCode :
2539481
Title :
Database replication using generalized snapshot isolation
Author :
Elnikety, Sameh ; Pedone, Fernando ; Zwaenepoel, Willy
Author_Institution :
Sch. of Comput. & Commun. Sci., EPFL, Lausanne, Switzerland
fYear :
2005
fDate :
26-28 Oct. 2005
Firstpage :
73
Lastpage :
84
Abstract :
Generalized snapshot isolation extends snapshot isolation as used in Oracle and other databases in a manner suitable for replicated databases. While (conventional) snapshot isolation requires that transactions observe the "latest" snapshot of the database, generalized snapshot isolation allows the use of "older" snapshots, facilitating a replicated implementation. We show that many of the desirable properties of snapshot isolation remain. In particular, read-only transactions never block or abort and they do not cause update transactions to block or abort. Moreover, under certain assumptions on the transaction workload the execution is serializable. An implementation of generalized snapshot isolation can choose which past snapshot it uses. An interesting choice for a replicated database is prefix-consistent snapshot isolation, in which the snapshot contains at least all the writes of locally committed transactions. We present two implementations of prefix-consistent snapshot isolation. We conclude with an analytical performance model of one implementation, demonstrating the benefits, in particular reduced latency for read-only transactions, and showing that the potential downsides, in particular change in abort rate of update transactions, are limited.
Keywords :
replicated databases; transaction processing; Oracle; database replication; generalized snapshot isolation; prefix-consistent snapshot isolation; read-only transaction; update transaction; Analytical models; Availability; Delay; Fault tolerance; History; Informatics; Performance analysis; Programming profession; Transaction databases; Web services;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Reliable Distributed Systems, 2005. SRDS 2005. 24th IEEE Symposium on
Print_ISBN :
0-7695-2463-X
Type :
conf
DOI :
10.1109/RELDIS.2005.14
Filename :
1541186
Link To Document :
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